As a fact, the supply of land is strictly limited by nature, while the other factors can and do increase. There are, however, several forces which neutralise or retard the tendency of land to become scarce, and of rent to rise. Modern methods of transportation, of drainage, and of irrigation have greatly increased the supply of available land, and of commercially profitable land. During the nineteenth century, the transcontinental railroads of the United States made so much of our Western territory accessible that the value and rent of New England lands actually declined; and there are still many millions of acres throughout the country which can be made productive through drainage and irrigation. In the second place, every increase of what is called the "intensive use" of land gives employment to labour and capital which otherwise would have to go upon new land. In America this practice is only in its infancy. With its inevitable growth, both in agriculture and mining, the demand for additional land will be checked, and the rise in land values and rents be correspondingly diminished. Finally, the proportion of capital and labour that is absorbed in the manufacturing, finishing, and distributive operations of modern industry is constantly increasing. These processes call for very little land in comparison with that required for the extractive operations of agriculture and mining. An increase of one-fifth in the amount of capital and labour occupied in growing wheat or in taking out coal, implies a much greater demand for land than the same quantity employed in factories, stores, and railroads.[60]